Originally Posted by catachrest

Sorry, but as a native speaker I must disagree with the opinions posted above. A dogcatcher is exactly what the name implies: a person employed to catch (stray) dogs. Nowadays we'd call them animal control officers, I suppose. "One rank up" means one step higher in a hierarchy (analogy to military or other similar ranked organizations). The speaker is giving a very poor opinion of the 'he' in the sentence, indicating that he is supposed to be a policeman, but is bad at his job and is little better than a dogcatcher. Note that dogcatchers aren't to my knowledge a member of the police ranking system! It's simply a way of saying how poor a policeman the speaker thinks this guy is. Hope that helps.